Tree-mendous Vancouver: A Deep Dive into the Blossom Streets!

UBC Key Capabilities in Data Science; Data Visualization Final Project

Author: Eric Hsieh

Introduction

Vancouver, unlike other major cities that boast iconic skylines, is renowned for its natural beauty. The city is a tapestry of beaches, neighborhood areas lush with greenery, and towering mountains that frame its skyline. Among its most celebrated features are the majestic trees that line the streets and the stunning cherry blossoms that adorn neighborhoods every spring.

As a photography enthusiast, I've often marveled at the captivating images of Vancouver's cherry blossoms shared online. However, I've also encountered the challenge of pinpointing the best locations to capture these scenes myself. This project is driven by my passion for both the natural beauty of Vancouver and photography, aiming to analyze the distribution of street trees and cherry blossoms across the city.

Questions of interests

  1. Which Vancouver neighbourhood has the most trees?
  2. What is Vancouver's top 10 most common tree species?
  3. How are cherry blossom trees distributed across Vancouver neighbourhoods?
  4. What is the relationship of trees' height and diameter?

Importing Data

This project will be using a subset of the Vancouver Street Trees dataset with 5,000 rows. We will be using the Vancouver city geojson using a URL from Vancouver Data Portal for geographical visualizations with Altair.

Data Description

The Vancouver Street trees dataset is said to include "a listing of public trees on boulevards in the City of Vancouver and provides data on tree coordinates, species and other related characteristics. Park trees and private trees are not included in the inventory. Data currency: The dataset refreshes daily on weekdays. Tree attributes are updated on a regular basis but it may be several years between updates for some attributes. Priorities and resources determine how fast a change in reality is reflected in the data."

A description for columns in the dataset that is needed for explanation.
Some columns are self-explanatory from its column name (e.g. neighbourhood_name is for neighbourhood name):

Column Description
ON_STREET The name of the street at which the tree is physically located on
SPECIES_NAME species name
NEIGHBOURHOOD_NAME neighbourhood name
DATE_PLANTED Date is in YYYY-MM-DD format.
Planted date of new trees is added after every planting season, usually at the beginning of January and June.
Note: Data for this field may not be available for all trees.
DIAMETER DBH in inches (DBH stands for diameter of tree at breast height)
GENUS_NAME genus name
COMMON_NAME common name
HEIGHT_RANGE_ID 0-10 for every 10 feet (e.g., 0 = 0-10 ft, 1 = 10-20 ft, 2 = 20-30 ft, and 10 = 100+ ft)
ROOT_BARRIER Root barrier installed (Y = Yes, N = No)

Before going into the data analysis and visualization, let's filter the dataframe with only the columns that will be used.
Here's a snapshot of how the dataset currently looks like:

This observation sees 5000 data entries, 21 total columns consisting of 8 numerical columns (float64 and int64). We're seeing some columns doesn't have 5000 entries indicating there are null values. Let's observe how many null values there are.

Question 1: Which Vancouver neighbourhood has the most trees?

A skeleton map of Vancouver will be generated first before we map the data and label the neighbourhoods.

This scatter plot shows the location of all the trees. However, this graph doesn't give us much useful information at first glance.

This visualization is informative as the size and shade of the circle is readable, but there is a much better way to communicate this data.

The choropleth map is a much better method to convey this type of information for area density. At a glance, we can quickly distinguish the area with dense trees by the shade of the colour.

Now, before graphing the cherry trees data points, we need to filter and defines the ones we want to display. I'm choosing to visualize the top 6 most popular cherry trees in Vancouver.

Now we add the neighbourhoods label and include the cherry tree points on click.

This map looks good with points coloured to resemble the different types of cherry trees.

Although this visualization method above hasn't been taught in this course, this implementation could be further explored for a future project. I will need to figure out how to accurately plot the Vancouver neighbourhoods boundary points to overlay onto this detailed map of Vancouver. For the sake of saving time and the aim for minimalistic visualization, I will continue with the choropleth map.

The choropleth map of Vancouver's neighborhoods shows the number of trees in each area. The map is colored according to tree count, with a colour gradient ranging from light yellow (fewer trees) to dark blue (more trees). From the map, we can see that Renfrew-Collingwood neighbourhood is highlighted as having the highest number of trees at 384 counts. The two neighbourhoods besides Renfrew-Collingwood comes close at second place for Kensington-Cedar Cottage with 375 trees and third place for Hastings-Sunrise with 340 trees. The Strathacona neighbourhood has the least amount of tree with a count of 75.

Question 2: What is Vancouver's top 10 most common tree species?

I want to have an interative bar graph with the vancouver map of the most common trees for each neighbourhoods on click. By default, it shows the most common trees for Vancouver city (all neighbourhoods combined).

From this graph, we can see the top 5 Vancouver's most common trees are Kawanzan Flowering Cherry, Pissard Plum, Norway Maple, Crimean Linden, and the Pryamidal European Hornbeam. It is interesting to see that the Vancouver West Side neighbourhoods doesn't even have Pryamidal European Hornbeam ranked in the top 20. Vancouver West Side has American Elm ranked 4th most popular and Crimean Linden ranked 5th most popular.

The Kwanzan Flowering Cherry has been consistently the top 3 most common trees for Vancouver neighbourhoods.

Question 3: How are cherry blossom trees distributed across Vancouver neighbourhoods?

This is the most exciting part of the Vancouver tree analysis! How are the beautiful cherry blossom tress distributed across Vancouver city? I will visualize this using bar chart interacting with the Vancouver map on click.

During springtime in Vancouver, the neighbourhood with the most cherry blossoms are Renfrew Collingwood, Mount Pleasant, and Dunbar-Southlands.

Arbutus-Ridge and Downtown only has 2 varieties of cherry blossoms, whereas in Grandview-Woodland and Mount Pleasant you will find a great variety of cherry blossom.

Question 4: What is the Relationship of trees' height and diameter?

We have two numerical data columns in our dataset; tree height and diameter. We will use the top 25 most common trees to answer this question. A scatterplot will be graphed with a visualization on the mean diameter line and a dropdown menu to view the "heigh and diameter" relationship of different trees.

The default view shows the data points of all the top 20 common Vancouver trees. We can see there is a general positive relationship between tree height and diameter. For all the tree species, we can also see a general positive relationship betwen tree height and diameter. Due to the lack of data for the tallest tree of each species, sometimes the data trend skews to a negative correlation at the higher "height range ID."

Dicussion & Conclusion

The trees of Vancouver not only provides the city with a beautiful scene, but it has a functional purpose to boost health and wellness such as clean air, provide shading, and creates shelter for wild animals. This data analysis provides a detailed exploration of the distribution and charatersitcs of Vancouver's street trees with a focus on cherry blossoms.

The map highlights the Renfrew-Collingwood neighborhood as having the highest number of trees, with a total count of 384. Kensington-Cedar Cottage and Hastings-Sunrise follow closely, with 375 and 340 trees. In contrast, the Strathcona neighborhood has the least number of trees, with only 75 counted. This distribution suggests a significant variation in tree density across Vancouver, with certain neighborhoods having a much higher concentration of trees.

Vancouver's top 5 most common trees are the Kwanzan Flowering Cherry, Pissard Plum, Norway Maple, Crimean Linden, and Pyramidal European Hornbeam. Using the multi-selection tool for multiple neighbourhoods, it is noteworthy to point out that the Vancouver West Side neighborhoods (borders from the west of Mount Pleasant, Riley Park, and Sunset) do not even rank the Pyramidal European Hornbeam in their top 20 most common trees. Instead, these neighborhoods have the American Elm as the 4th most popular and the Crimean Linden as the 5th most popular tree. This observation highlights the regional variations in tree popularity within Vancouver.

The Kwanzan Flowering Cherry consistently ranks among the top 3 most common trees in Vancouver neighborhoods. This consistency showcases the tree's popularity and its significance in the Vancouver urban landscape in the spring season. During springtime, the neighborhoods with the most cherry blossoms are Renfrew-Collingwood, Mount Pleasant, and Dunbar-Southlands. The variety of cherry blossoms is also notable, with Grandview-Woodland and Mount Pleasant offering a wide range of cherry blossom species. In contrast, Arbutus-Ridge and Downtown only feature 2 varieties, which may reflect different urban planting strategies. Different cherry blossom species have different blossoming times and duration. It would be interesting to do analysis to see if cherry blossom blooming time have a relationship to planting stragegies.

In conclusion, this analysis of Vancouver street trees reveals insights into the distribution and characteristics to the city's urban forest planning. The data shows a widespread of cherry blossom trees particularly in neighborhoods like Renfrew-Collingwood, Mount Pleasant, and Dunbar-Southlands, which are rich in variety and tree density.

The observation of tree species popularity between different areas, such as the distinct preferences in Vancouver's West Side neighborhoods, suggest that urban planning and community preferences play a crucial role in shaping the city's tree canopy.

The relationship between tree height and diameter observed in the scatter plot suggests potential avenues for future research, including exploring whether taller trees (as a potential indicator of older neighbourhoods) are more common in wealthier neighborhoods. Future projects could also involve a deeper investigation into the socioeconomic factors influencing tree distribution in Vancouver. Additionally, exploring the environmental and aesthetic impact of tree types in urban areas could provide valuable insights for city planning and conservation efforts.

This analysis not only sheds light on Vancouver's current state of tree distribution, it also lays a foundation for future urban forest planning aimed to enhance the city's natual beauty and sustainability.

Dashboard

References

Data Source:
Vancouver Street trees by the City of Vancouver

Article that sparked interest:
CBC - Why Metro Vancouver's cherry blossom trees offer more than just a pretty picture